The present invention relates to a gripper assembly and more particularly to a gripper assembly which is operable between a fully open position and any one of a plurality of closed positions to enable the gripper assembly to grip articles of different sizes.
A known gripper assembly for gripping sheet material articles, such as a newspaper, is disclosed in U.S. Pat. No. 4,381,056. The gripper assembly disclosed in this patent has a movable clamp member or tongue which is held in clamping engagement with an article by a pawl arrangement. The pawl arrangement includes a wheel which is connected to the movable clamp member. After the wheel has been rotated to a predetermined position, a pawl engages a gap in the wheel to hold the gripper in clamping engagement with an article. In order to enable the pawl to engage the gap, the wheel must be rotated to the same position each time an article is to be gripped.
The gripper assembly disclosed in U.S. Pat. No. 4,381,056 may be used to grip newspapers. Newspapers may have outer sections formed of a relatively rough paper which is easy to grip and an inner section formed of a relatively smooth paper. Due to the low coefficient of friction of the surface of the inner section of the newspaper, the inner section of the newspaper may tend to slip out of the outer section of the newspaper while the newspaper is held by a gripper assembly.